Switch construction



March 18, 1941. w. E. HAsELwooD SWITCH. CONSTRUCTION Filed Nov. 50, 193B 2 Sheets-Sheet 1 INVENTOR.

March 18, 1941. w, E HASELWQOD 2,235,366

SWITCH coNsTRUcTN Filed Nov. 50, 1958 2Sheets-Sheet 2 s: ll

Hlm Il WMIIM i INVENTOR.

ATTORNEYS.

Patented Mar. 18, 1941 UNITED STATES SWITCH CONSTRUCTION Willis E. Haselwood.

Ind., 8818110! i Chl.

Elkhart, cago Telephone Suppl! Company, Elkhart, Ind..

a corporation of In Application November so, 193s, sorua No. 243,081

. 2 8 Claims.

'Ihis invention relates to a new and improved switch construction and more particularly to a shielded switch of the snap or toggle type.

Switches of this character are especially adapted for use with radio apparatus, such as radio receivers, or test equipment, and in public address systems or the like. In many such circuits it is desired to locate switches closely adjacent other control units, which control units are connected into the circuit at points where any hum or other disturbance picked up from the switch will be highly amplified. It is customary to use such switches directly connected to variable resistances which are connected into and control earlier stages of high gain circuits. If the switch is used to control alternating current there may be picked up from the switch an audible hum which will thereafter be so ampliiied as to ne highly objectionable. The same eects are present where the switches are used in controlling battery circuits in which vibrators are used for stepping up the voltage.

In prior constructions the switch has been shielded from the adjacent control unit in various 5 manners. A iixed shield has been provided between the adjacent units, with an eccentric opening through which the switch operating mechanism extends. Any opening through the shield permits some transfer oi electrical disturbances 3U to pass. Also the construction requires a separate shield or a multiplicity of housings, one for the switch and one for the other control unit, which adds to the expense.

An alternate form of construction has been the 35 provision of a rotating shield carried by and rotated by the shaft controlling the units. This rotating shield has the undesirable eiect of adding to the expense and also constitutes a grounded member closely adjacent the parts of thev sec- 40 ond control unit which may result in undesirable capacity coupling between that unit and ground. According to the present construction, I have placed the shield directly upon the switch, which is the unit carrying the current having the dis- 45 turbing characteristics. There are no undesirable eiects from placing the grounded element closely adjacent the current carrying switch elements, if the parts are properly insulated. This construction also makes it possible to eliminate separate shield partitions and to carry the switch directly upon a wall of the housing used to enclose the second control unit. The construction, therefore, results in close shielding of the switch itself and in the reduction of cost of parts and 55 saving in space.

(Cl. 20o-67) It is an object vof the present invention to provide a new and improved switch having a self contained shield.

It is a further object to provide a switch having a shield as a portion of the switch arm as- 5 sembly and movable with the movable contact.

It is also an object to provide a switch in which the movable shield is electrically connected to the switch actuating means. t

It is. an additional lobject to provide a switch of this character associated with a metallic housing to which the switch actuating means is grounded at its limits of movement.

It isa further object to provide a shielded switch and housing assembly adapted for use with other control units and in which the switch will be adequately shielded from other units Within the housing. 7

Other and further objects will appear as the description proceeds. 2o

I have shown certain preferred embodiments of my invention in the accompanying drawings, in whlch- Figure 1 is a face view ofthe switch, with the parts in the o position; o

Figure 2 is a view of the construction of Figure 1 as seen from the left, with the housing broken away;

`Figure 3 is a View similar toFigure l but show ing the switch in the closed position'i Y 30 Figure 4 is a section taken on line 4-4 of Figure 3: o

Figure 5 is a view similar to Figure 3, but showing a modied, form.o'f construction; and

Figure 6 is asection taken on line 6--6 of Fig- 35 ure 5.

Referring rst to Figures 1 to 4, the non-conducting base member Il is supported in one end of the housing l2, which latter is formed of metal and functions as a shield surrounding the pe- 40 riphery of the switch. The housing l2 is shown as provided with lugs I3 by means of which it can be secured to a base or to another circuit control device. It will be understood that the housings may be formed of different shapes and proportions and may be deeper than the housings shown, so that the single housing can enclose a plurality of units. The pivot member I4 is secured to the base Il and carries the metallic operating cam I5. This cam engages a shoulder I6 50 on the pivot and is held in place by the deformed end I1 or the pivot which engages the washer i8.

The switch arm assembly comprises the metallic member i9, which is provided with the enlarged opening ittlng around the portion 20 of 55 each provided with the upstanding lugs 21, these two lugs 21 tting into an enlarged recess 28 in the member 23. The movable contact member 24 is held between the base plate II and the switch arm assembly, and the intertting lugs 25 and 21 cause it to be moved with the switch arm assembly, although allowing a limited play whereby this movable or bridging contact may properly adiust itself to intertlt between the two fixed contacts 29 and 30 which are carried by the base plate II. These iixed terminals 29 and 30 are provided with the solder lugs-3| and 32 upon the upper face of the base plate II.

The housing I2 is provided with an inwardly pressed portion 33 which serves as a limitingstop for movement of the operating cam l5. This cam I5 is generally U-shaped in construction and its lower leg is provided with the stop extension 34 adapted to engage this portion 33 of the housing with the switch in the closed position, as shown in Figure 3. The opposite end 35 of the operating cam engages the other side of the housing portion 33 when the parts'are in open position, as shown in Figure 1.k 'I'he upper leg of the operating cam I5 is provided with the rounded portions 36 and 31 adapted to be engaged by a driving member for operation of the switch. The lower leg of the operating cam is provided with the inward extension 38 having a perforation 39 into which is tted one end 40 of the coil spring 4I. The opposite end 42 of this spring extends through a perforation 43 formed in the metal plate I9. 'I'his construction forms a toggle action by means o1' which the. switch arm assembly is snapped into and out of vclosed position as the operating cam and spring 4I are moved past the dead center position in the two directions of movement.

As shown in Figure 3, with the switch in the 4closed position, the bridging contact member 24 effectively closes the circuit between the two xed contacts 29 and 30. The spring 4I, in addition to serving as a resilient driving connection for the toggle operation, also is so biased as to urge the switch arm assembly downwardly toward the base plate II, thus maintaining the bridging contact 24 held down against the base plate II for proper operation. It will be noted that in Figure 3 the switch assembly doesznot engage the housing I2. The entire stopping action when the switch is moved to a closed position is afforded by the resilience of the bridging contact 24 as it engages and wedges between the switch contacts 29 and 30. w

It will be apparent that the metal plate I9 fully covers both the xed contacts 29 and 30 and the bridging contact 24 so that it effectively shields them and prevents: passage of any disturbing electrical effect therefrom in the direction covered by the shield. This metal plate4|9 is electrically connected to the pivot l1 by its pivoting contact therewith. It is also electrically connected to the pivot through the drive spring The legs of the member 24 are also y 4l and the operating cam l5 which is formed of metal and mounted directly on the metallic pivot. Due to the engagement of the stop portions of the cam I5 with the inwardly extending portion 33 of the housing, the switch plate I9 is always electrically connected to the housing I2 when the switch is in closed position. It will be understood that when the switch and housing are assembled upon any supporting structures, such, for example, as the housing of another unit or a base carrying another unit, the housing will be grounded through this support.

Referring now to the form of construction shown in Figures 5 and 6, the parts are generally similar with the exception that the shield plate does not serve to connect the switch arm assembly to the pivot. The insulating base 5I is supported in a metal housing 52, which is shown as broken awayin Figure 6. It will be understood that this housing may be of any suitable depth or dimension to enclose other control units adapted to be A operated jointly with the switch. The pivot member 53 is fastened into the base 5I by riveting over its head 54. The enlarged portion 55 of the pivot 53 .bears against the Vinner face of the base 5I and its opposite face serves to limit movement along the pivot by theswitch arm 56, which is formed of insulating material. The circumferential ridge 51 on the. pivot 53 serves to limit movement of the switch arm in the opposite axial direction. y

'I'he operating cam 58 engages the shoulder 59 formed on the pivot 53. This cam 58 is rotatable about the reduced portion 60ct the pivot and is held in place by the head 6I of the pivot riveted over against the outer face yof the cam 58. s 'Ihe xed contacts 62 and 63 are supported in the `base 5I and are connectedlto the solder lugs 64 -and described in connection therewith, having portions iitting in recesses formed in the insulating switch arm 56. The insulating plate 61 is placed against the upper face of the switch arm 56 and serves to insulate themovable contact 66 from the shield plate 68. This shield plate 68 is secured in position upon the switch arm 56 by the downturned and inturned lugs 69. 'I'he coil spring 18 is connected to the operating cam 58 and has its opposite end tting in an opening 1I in the shield plate 68. It will be apparent that this spring, therefore, serves to electrically connect the operating cam 58 and the shield plate 68. The operating cam, as shown in Figure 5, has

of the housing 52 when the switch is in closed position. This serves to connect the cam 58 to the grounded `housing 52 and, through the medium ofthe springvl, the shield plate 69 is also grounded. l

Thenform shown in Figures 5 and 6 operates in the same manner as the form shown in Figures 1 to 4. The only substantial diierence between the two is that the metal shield 68 of the form of Figures 5 and 6 does not `constitute the switch arm and does not engage the pivot.

While I have shown certain preferred embodiments of my invention by way of example, it will be understood that these are illustrative only, as the switch and its housing are capable of modirlcation and change to meet varying conditions and requirements and I contemplate such variations as come within the spirit and scope of the appended claims.

55 the portion 12 engaging the indented portion 13 I claim:

1. In a switch of the character described: a housing having a metal side wall and a non-conducting end wall providing a base; a stationary contact carried by the base and exposed on the inner face thereof; a movable contact; an insulated carrier member lfor'the movable contact; a metal shielding member connected with the carrier member and overlying the same on its side remote from the base, said metal shielding member being large enough to cover the contacts in any position of the connected carrier and shielding members; means pivotally mounting said con nected members for swinging movement inside the housing to carry the movable contact to and from engagement with the stationary contact; a metal actuating cam pivotally mounted inside the housing; means electrically grounded to the housing side wall engageable with the cam for limiting movement thereof between two dened positions and for electrically grounding the cam to said housing side wall; and a snap spring connected between the metal actuating cam and the metal shielding member for snapping said connected members from one position to the other as the actuating cam is operated and for electrically grounding the shielding member through the cam to the housing side wall.

2. In a switch of the character described: a

housing having a metal side wall and a non-conducting end wall providing a base; a stationary contact on said base exposed on the inner face thereof a movable contact; a metal shielding member overlying the base in substantially parallel spaced relation thereto, with the contacts between it and the base; means pivotally mounting said metal shielding member for oscillation across the 'inner face of the base; an insulated connection between the movable contact and said metal shielding member whereby the movable contact moves with the shielding member for coaction with the stationary contact; a metal actuating cam mounted within the housing for oscillation about a xed axis between predetermined limits; means for dening said limits of oscillation of the cam and for electrically grounding the cam to the metal side wall of the housing; and a snap spring connected between the metal actuating cam and said metal shielding member for snapping the shielding member and consequently the movable contact from one position to the other as the cam shielding member through the cam to said side wall of the housing.

3. In a switch of the character described: a ilat insulating base; a stationary contact on the base; a pivot post projecting from the base; a movable contact; a carrier for the movable contact pivoted on said post for planar movement across the base, said carrier including a metal shielding plate in substantially parallel spaced relation to the base, with the contacts between it and the base; and a toggle snap mechanism for actuating the movable contact carrier comprising a metal actuating cam pivotally mounted on said post, and a snap spring connected between said cam and the metal shielding plate whereby said shielding plate, spring and metal actuating cam are electrically connected so that grounding of any one grounds all of said elements.

4. In a snap switch of the type adapted for use in radio circuits; stationary and movable contacts; a carrier for the movable contact, said carrier including a metal shielding plate overlying the contacts and large enough to cover them in shielding plate to prevent the transmission of electrostatic or electromagnetic eilects from the yswitch to other electrical instrumentalities adjacent to the front of the switch.

5. In a snap switch: stationary and movable contacts; a carrier for the movable contact including a metal shielding plate `overlying the contacts and large enough to cover them in all positions of the carrier; means mounting the carrier for switch closing and opening movement; snap actuating means for snapping the carrier from one position to the other comprising a metal actuating cam, and a lost motion driving connection between the cam and the carrier, said lost motion driving connection serving to electrically connect the metal shielding plate with said actuating cam; and means for electrically grounding the actuating cam. y

6. Ina snap switch of the character described: a non-conducting base; a metal pivot post; an actuating cam mounted on said post; a stationary contact carried by the base; a movable contact; a carrier for the movable contact including a metal shielding plate overlying the base in substantially parallel spaced relation thereto, with the contacts between it and the base, said shielding plate being large enough to cover the contacts in all positions of the carrier and said metal shielding Plate being pivotally mounted on said pivot post so as to be electrically connected with the post; a snap driving connection between the carrier and the actuating cam whereby actuation of the cam snaps'the carrier from switch open to switch closed position and vice versa; and means for electrically grounding the pivot post.

7. In a snap switch of the character described: a non-conducting base; a metal pivot post: a

.metal actuating cam moimted on said post; a

stationary contact carried by the base; a movable contact; a carrier for the movable contact including a metal shielding plate overlying the base in substantially parallel spaced relation thereto, with the contacts between it and the base, said shielding plate being large enough to cover the contacts in all positions of the carrier and said metal shielding plate being pivotally mounted on said pivot post so as to be electrically connected with the post; a snap driving connection between the carrier and the actuating cam whereby actuation of the cam snaps the carrier from switch open to switch closed position and vice versa; and a metal stop capable of being electrically grounded and engageable with the metal actuating cam to define its limits of movement and electrically ground the cam, post, and shielding plate.

8. A snap switch of the type described comprising: a non-conducting base: a metal wall encircling the base and cooperating therewith to form a substantially cup-shaped housing; a pivot post projecting from the inner face of the base near the metal side wall but spaced therefrom; a pair of stationary contacts carried by the base and exposed on its inner face; a movable bridging contact for electrically bridging the stationary contacts in switch closed position; a carrier for the movable bridging contact pivoted on the connecting the shielding plate with the metal cam; and means for limiting motion of the metal actuating cam, said means being electrically conductive and electrically connecting the metal cam with the metal side wall of the housing when the cam is at either of its limits of movement so that grounding of said side wall electrically .grounds the cam and consequently the shielding plate.

WILLIS E. HASELWOOD. l0 

